Method of explosively forming fibers



Jan. 19, 1965 1. E. BENTOV METHOD OF EXPLOSIVELY FORMING FIBERS.

Filed May 16, 1962 2 Sheets-Sheet 1 FIGS TTO NEYS Jan. 19, 1965 l. E. BENTOV 3,165,826

METHOD OF EXPLOSIVELY FORMING FIBERS Filed May 16, 1962 2 Sheets-Sheet 2 H6 7 FIG. 8

FIG. 9 T 66 ATTORNEYS United States Patent ()1 Sly The present inven ion relates to a method of explosively forming structures from fibers and to structures formed from fibers in accordance with a novel process.

This invention is particularly concerned with a method of explosively forming structures using thermally deformable fibrous materials and in panticular, metal fibers as a starting material. The invention contemplates the formation of a shaped solid structure in a controlled manner from such fibers utilizing an explosive forming or similar technique. Heretofore sheet material and powder have been deformed into selective configurations by such techniques. in such techniques a work piece is arranged adjacent a restraining means, normally a female die surface. Means for creating a rapid discharge of energy are positioned on the other side of the Work piece so that when energy is rapidly discharged the work piece will be deformed and compacted by intense pressures and heat to the shape of the female die. Normally the energy discharge is supplied by an explosive such as dynamite, TNT RDX, PETN, etc. However, other sources of energy have also been used and include, for example, an electrohydraullc energy source consisting essentially of an electrical circuit having a rapidly dischargeable capacitor with the discharge terminals under water so that a rapid discharge across the terminals causes the formation of a shock wave caused by the rapidly expanding gases in the water. A substantially instantaneous generation of a high density magnetic field may also be used as an energy source. While the techniques used serve a useful function in rapidly forming integral and complicated forms in an inexpensive manner, the techniques developed have certain inherent limitations in respect to the shapes that may be formed.

Accordingly, it is the principal object of the present invention to provide a process of making shaped structures and particularly metal structures having walls of varying but selected thicknesses or cross sections.

It is an object of the present invention to provide a method whereby a rigid shape may be formed from a self supporting, pliable, formable material, as a web of metal fibers.

It is also an object of the present invention to provide a method of forming structures, particularly of metal, with a selected degree of porosity. Such porosity may be locally controlled and may be used for filter and other purposes.

It is also an object of the present invention to provide a method of forming a structure, particularly of metal, wherein the mechanical strength of the structure can be controlled within limits by selective orientation or disorientation of the fibers which are used to form the structure during the manufacturing process. Thus structures may be formed having unusual degrees of strength by virtue of selective orientation of fibers forming the structure during the manufacturing process.

A further object of the present invention is to provide a method of forming shaped structures having selected physical and chemical properties. For example, the present invention provides a method wherein shaped structures having thermoelectric properties may be formed by utilizing fiber materials of metals having thermoelectric properties and in which alloys are formed which display such properties. Formation of structures from whiskers of various metallic or non-metallic ele 7 3,165,826 Patented Jan. 19, 1965.

ments are contemplated. Whiskers can be formed of many elements such as zinc, tin, copper, carbon, sapphire, quartz, silicon and iron. Such whiskers are impacted and fused into a unitary structure in sucha short time duration that the fwhisker crystals do not have time to recrystallize and thereby change their properties. These whiskers are single filamentary crystals of elements having a large length to diameter ratio, with, an almost perfect atomic structure which gives them unusual strength.

A further object of the present invention is to provide structures formed of fibers of-a multiple number of elements which when impacted together according to the present invention display novel physical, chemical and electrical properties.

A preferred embodiment of the present invention for forming shaped structures includes a process in which a quantity of fibers, usually metal fibers, are arranged in a web of selected thickness with the fibers of the web' being selectively oriented or disoriented, depending upon the desired results. The web is positioned adjacent a restraining means which may comprise a die having a surface conforming to the desired shape of the structursbeing formed. Means for rapidly discharging sufiicient energy over a very short time period to compact or fusethe fibers into an integral mass against the surface the restraining means are positionedon the-side of the web The extreme pressures and. temperature generated by i this sudden energy discharge cause the fibers to compact and fuse into an integral shapehaving a surface configuration conforming to the restraining means surface.

- These and other objects and advantages of the'pre s ent invention will be more clearly understood when considered in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic cross-sectional'view illustrating. apparatus for use in a process embodying a preferred form of the invention;

FIG. 2 is a cross-section of a typical structure'formed by practicing the-preferred form of the present invention;

FIG. 3 is a schematic cross-section of a fibrous web with the fibers longitudinally oriented for use in the present invention;

FIG. 4 is a cross-sectional view of nonoriented fibers forming a web; V

FIG. 5 is a schematic enlarged cross-section of a fragment of a structure compacted in accordancev with this mvention;

FIG. 6 shows a cross-section similar to FIG. 5 wherein a formed structure is partially fused;

7 FIG. 7 is a cross-section illustration of a fragment of a structure similar to FlG. 6 but with a. greater amount of fusion;

FIG. 8 illustrates a cross-section similar to FIG. 7 with a still furtheram ount of fusion;

FIG. 9 illustrates a cross-sectional view similar to l; but with through pores'formed wherein the structure is adapted to function as a filter; a

FIG. 10 illustrates an apparatus for use in practicing I an alternate embodiment of. the invention, and

FIG. 11 illustrates a schematic cross-section of appara tus useful in practicing a still further embodimentof' this invention.

The present invention is directed primarily toward the. formation of metal structures from metal fibers. However, structures may also be formed from other fibrous material capable of being fused or compacted by a high rate discharge of energy. Such other fibrous material may include synthetic organic fibers, fibers of semi-conductive materials or other non-organic fibers such as refractory fibers. Combination of fibers of different materials may be used or alternatively fibers may be mixed with powders, discrete particles or small crystals to form alloys or pseudo-alloys of desired physical properties. The invention also contemplates the use of metal-nonmetal combinations, such as metals with powdered graphite, molybdenum disulphide or other materials to affect the frictional surface of the structure. Structures having thermoelectric properties formed of fibers of thermoelecric elements such as chrome-nickel, bronze, lead tellurium or lead-selenium are also contemplated.

The invention also contemplates the forming of structures from single crystals of metal in whisker form. These whiskers normally have a large length to diameter ratio and unusual tensile strength. For example, the tensile strength of an iron whisker 2 microns in diameter normally is in the range of 1.9 million p.s.i. which is approximately fifty times greater than the tensile strength of ordinary iron. It is calculated that a structure formed from a web of randomly arranged whiskers may have tensile strengths in the vicinity of 700,000 to 800,000 p.s.i. Where an oriented web of such whiskers is used as herein-after described, greater tensile strengths of the finished structure are possible.

The fibers from which the present invention is formed are arranged in a web of preselected size. The widths and lengths of the web should be suflicient to permit the web to confirm with the die over which it is fitted. The thickness of the web may be uniform or nonuniform depending upon the desired results. If certain parts of the formed structures are to be thicker than other parts the web will be varied in thickness or density and shaped accordingly. In a preferred embodiment of the present invention wherein a metal structure is formed of metal fibers, the fibers themselves may be varied over a wide parameter of lengths and diameters. Exemplary param eters are suggested by the length and diameter of ordinary metal fibers which are used as steel wool. The fibers may also be oriented or non-oriented. FIG. 3 illustrates a quantity of fibers 1 longitudinally oriented with respect to the web. These fibers are slightly matted or intermeshed so as to hold the form of the Web. The fibers are flexible to permit the forming and shaping of the web. Oriented fibers such as illustrated in the web of FIG. 3 are preferred if the structure which is to be formed is to have improved structural strength in the direction of the fibers. If desired the fibers may be non oriented as illustrated in FIG. 4. These non-oriented fibers which are heavily matted or intermeshed may be formed into a structure having relatively uniform structural strength along different axis.

The Web 2 as thus formed is contained in an envelope 3 (FIG. 1). This envelope is preferably formed by thin sheets of flexible nonporous material. Preferably these sheets are formed of synthetic plastic such for example as polyethylene. The bag or envelope is sealed at its periphery 4 to form a closed container. This envelope is then positioned over a surface 5 of a die 6. The surface 5 is contoured or shaped in the form of a female die surface to the desired shape of the structure to be formed. The envelope may be shaped with the web having uniform thicknesses throughout or, alternately, may be shaped with certain portions, as for example those illustrated at 7 and 8, having greater thicknesses than other portions, such as illustrated at 9. The surface 10 of the bag adjacent the surface 5 of the die 6 should be close fitting to the surface 5. Air is evacuated from the envelope 3 by suitable means such as the vacuum pump 12 which is connected to the bag 3 by means of pipes 14 suitably sealed at the juncture 15 of the pipes and the bag. This compresses the fibers to form a relatively soft self supporting structure. If desired inert gas supplied through valve 17 and pump 18 may be used to flush the fibrous body for purposes of removing all traces of air and oxygen. The removal of air and oxygen is particularly important where it is desirable to avoid oxidation of the fibers or the structure being formed. Air is also removed between the envelope 3 and the surface 5 of the die 6 by means of the pump 20 and pipes 21 which open at 22 onto the surface 5. This pump is used not only to remove the air from between the envelope 3 and surface 5 but also to aid in securely holding the envelope 3 against the surface 5.

A thin metal shield 24, in a preferred embodiment, may be positioned over the envelope 3 or inside the envelope in contact with the metal fibers if a smooth surface is needed. This thin metal shield is used to protect the fibers from the blast which is to be generated. The shield may be formed of a wide variety of thin metal materials, as for example, brass, stainless steel and steel. The impact energy of this shield is converted into thermal energy in the fibrous mass thus aiding in the fusion and compaction thereof. The metal shield should conform generally to the contour of the fibrous mass in the die. If a structure such as illustrated in FIG. 2 is to be formed, the shield 24 should have a configuration generally corresponding to surface 25, while the surface 5 of the die 6 should have a surface confirming to the surface 26 of the structure 28. It will be noted that the structure illustrated in FIG. 2 has thicker portions 29 and 30 than portion 31. These correspond with portions 7, 8 and 9 of the web 2.

The envelope 3, die 6 and shield 24 are immersed in a fluid 3 5 in the container 35. This fluid is preferably water but may comprise other pressure and heat transmitting mediums. An explosive charge 37 is positioned in spaced relation to the shield 24 and is connected by wires 38 to a suitable detonator 39.

The energy source should permit a rapid forming of the product. High energy rate forming speeds suitable for this invention may be defined as speeds at which the metal is being forced toward the restraining means at speeds of f.p.s. and higher, depending on the mass of the metal to be accelerated and resistance to deformation, as compared with about 5 fps. for conventional forming techniques. The energy source is preferably a means for generating a detonation, but other rapid high energy discharges are possible. Thus any suitable type of explosive may be used. In the illustration the explosive comprises PETN in a plastic base, however, it may be formed of sheet explosive contoured to rest against the shield 24.

Instead of using conventional explosives the invention also contemplates the use of energy discharges from electric spark discharges under water of the type described in The Tool Engineer, March 1960 edition. In this system a high voltage power supply maintains a capacitor bank at a high energy level. The capacitor bank is discharged rapidly through electrodes positioned underwater and adjacent to the fibrous webs. This spark discharge generates a shock wave essentially from a point source through the fluid medium of sufficient magnitude to deform the metal part.

Other energy sources for rapid discharge of energy may also be used including the use of explosive gas mixtures. Where an explosive gas mixture is used the mixture itself functions as a fluid medium with the gas contained in a substantially enclosed and reinforced container in place of container 35. The explosive gas mixture will of course assume the shape of the container and therefore becomes an optium shaped charge regardless of quantity, with the mixture in intimate contact with the work piece or, if desired, shield 24. Such gas mixtures may comprise a mixture of oxygen and hydrogen in a ratio of one atmosphere of oxygen to three atmospheres of hydrogen. In a typical system the chamber or container is normally purged with a suitable gas such as nitrogen after which the gas mixture is introduced. The use of explosive gas mixtures in place of solid explosives in certain instances has been explored. See The Tool and Manufacturing Engineer, January 1962 edition, pages 61 to 68. Other explosive sources referred to in the preceding article are also contemplated.

n detonation of the explosive charge 37 or other equivalent charge, shock or pressure waves are generated which radiate from the explosive source and/or are directed towards the surface of the envelope 3 to compact, heat and/ or fuse the fibers contained within the envelope. Depending upon the various parameters used including the nature of the fibers and the web, the amount of explosive, its distance from the fibers (stand-off distance), the transmitting medium and other factors, the web will be compacted and/or fused to varying degrees. The web 2 may be compacted into a relatively dense and fused shape such as illustrated in FIG. 2. In cross-section, the fibers may be compacted and/or fused into varying degrees of density such as illustrated in FIGS. 5 to 9 inclusive. In FIG. 5 there is illustrated a structure in which the fibers have been compacted but not fused. Here the individual fibers I are compressed to a relatively compact form but are not actually fused together at their interstices. The outer fiber areas illustrated at 40 and 41 are relatively more compacted than the fibers at the center 42. This arrangement can be attained by utilizing an explosive force and other parameters such as to exert a compacting force but not sufficient to raise the temperature of the fibers to a melting point at which they will fuse or weld at their interstices. In FIG. 6 the impacting force used to form the configuration is somewhat greater than that illustrated in FIG. 5. Here the fibers l are fused or welded as illustrated at dd at their interstices. Again the outer portions of the structure have a greater amount of compaction than the inner portions. In FIG. 7 a greater impacting force is utilized than that used to attain the configuration illustrated in FIG. 6. Here there is substantial fusion on the fibers to form homogeneous masses on the outer portions 47 and Q3. The center portion 49 has relatively less dense areas with the fibers I still having their distinct configurations but nonetheless fused at their interstices as indicated at 44. The embodiment of FIG. 8 illustrates a compacted structure in which still further energy was used to form the structure than that of FIG. 7. Here the structure has formed a substantially fused mass with a few incompletely compactedareas 49 located primarily in the center portion of the structure. FIG. 9 illustrated an arrangement wherein the fibers are arranged so that on compaction pores 50 are formed which extend through the structure from one surface 51 to the other. This configuration may be useful in the formation of specially shaped filters or the like. The configurations shown in FIGS. 5 to 9 inclusive are not necessarily drawn on related scales, since the use of an increased amount of energy for compacting and fusing, other parameters being equal, would result in structures having narrower thicknesses.

The specific embodiment illustrated in FIG. 1 may not be most desirable for all uses. For example, the explosive charge illustrated in FIG. 1 is spaced from the fibers. This means that a relatively greater amount of energy must be utilized than if the explosive charge were in intimate contact or immediately adjacent to the fibrous web. In addition the plastic envelope 3 is in juxtaposition to the fibrous web and therefore will be forced intothe metal, and under certain conditions might contaminate it on the occurrence of the blast. FIGS. 10 and 11 illustrate modifications wherein these problems are minimized. In FIG. 10 there is illustrated an embodiment for forming fiat sheets from fibrous webs. Here the fibrous web 69 is interposed between two inner rigid sheets or shims preferably formed of a metal such as steel. The web and these shims 61 are encased within a bag or envelope d2 suitably sealed at its periphery and connected to a vacuum pump source 63 by means of pipes 64. A sheet explosive 65 suitably connected by wires 66 to the detonator 67 is positioned parallel to the bag or envelope 62. This explosive may be any suitable explosive such for example as Du Fonts EL-506 sheet explosive. This explosive is made up of PETN (pentaerythritol tetranitrate) in a plastic base. This explosive may create'pressures estimated to be about four million pounds per square inch at the surface of the explosive sheet. If this explosive force is too great the explosive may be spaced from the bag 62 by means of a standolf element d9. Such standoff element may consist of a number of sheets of kraft paper or the like. The assembly is taped together to hold the explosive sheet tightly against the shims 61, and the assembly is immersed in a liquid such as water 76 in the container 71. The bag is partially evacuated before detonation. On detonation of the explosives 65 the web 61 may be compacted into a homogeneous mass such as illustrated in FIGS. 5, 6 or 7. The surface of the structure formed conforms with the surface of the shims 61. Thus relatively smooth and shiny surfaces may be attained on the'end product or structure. If no standolf element is used a product more closely resembling those schematically illustrated in FIGS. 7 and'8 are possible.

FIG. 11 illustrates a still further modification wherein an envelope containing fibers and shims conforming with those illustrated in FIG. 2 is placed on an anvil 74. A standoff sheet or sheets 69 of thick paper is positioned above the envelope 62; and a suitable explosive charge 75 is positioned above the standoff sheets. Air is partially evacuated from the envelope. The explosive charge 75 is detonated by means of the detonator 76. In this arrangement the anvil '74 acts as a positive die. If desired, the entire assembly may also be immersed in Water.

The amount of energy required varies considerably depending upon the part to be formed and the degree of compaction or fusion desired. It has been found energy sources capable of generating between 3,000 p.s.i. ,to 8 million psi. at the surface of the fibers are desired. The energy should be discharged in a relatively short time. While this time period may vary, .01 second would appear a reasonable maximum time period within which the total energy is to be discharged. However, experiments have been conducted in which energy in the ranges indicated have been discharged in about 15 microseconds to generate detonating waves having a velocity of about 23,000 fps. to 28,000 fps.

The fibers of the web are-compacted or fused by a combination of the pressure waves and high instantaneous temperatures which are developed in the web. perature rise is due to several factors. In an arrangement such as illustrated in FIG. 11, nine factors control the temperature rise. They include: (1) adiabatic con pression of gases in the fibrous mass, (2) frictional work done by compacting the fibrous mass, (3) elastic deformation work done on the fibers in the process of compaction, (4) impact of the fibrous mass on the anvil during the process of compacting, (5) the impact of the top shim or sheet on the fibrous mass, (6) the combustion of oxidizable fibers in any oxygen that is available, (7) the heating of the steel sheet by radiation from the explosive discharge, (8) the elastic formation of the top sheet or shim,

(9 the elastic deformation of the bottom sheet or shim.

Gf these sources of heat, the more important onesare the first six. If the bag or envelope is completely evacuated of air the first and sixth factors are notof concern as no heat can be generated due to adiabatic compression andno, combustion can take place. The temperate rise is determined by the heat capacity of the whole system and in particular of the work piece or'fibrous web. Controlled amounts of various gases such as inert gases as argon and neon and other gases as hydrogen, oxygen, etc., may be substituted for air to vary the rate of fiber temperature rise.

The tem- Important parameters of the system include the amount of the fibrous mass, its consistency, the thickness of the fibers, the specific heat of the fibers and the type of fiber material. If the system used includes a gaseous envelope about the fibers the thickness of the fibers are of particular importance. The fiber thickness determines the area exposed to radiation of hot gases. Therefore, the finer the fiber the larger the exposed area and the faster will be the temperature rise. Thus, where a selected fiber is to be used for varying applications, and the amount of fiber, explosive means, standoff, shim thickness and vacuum are maintained as constants from one application to another, variations in resultant structures may be obtained by varying the thickness of the fibrous mass to control the degree of fusion.

Several experiments have been conducted which exen plify various embodiments of the present invention. These experiments include the following:

Example 1.-Grade 0000 steel wool weighing approximately 10 grams with the steel wool fibers generally oriented in the same direction was arranged in three layers having uncompressed dimensions of 1" x 4" x 5". This multilayer web was sandwiched between two layers of .015" thick steel shim stock. The sandwich thus formed was placed in a polyethelene bag and taped together. The thickness of the sandwich was compressed at this point to approximately A" in diameter. The assembly was laid flat on a steel anvil, a rubber balloon filled with water was placed on top of the sandwich for purposes of distributing pressures generated by the explosive charge. A 4" x 5" sheet of Du lonts El-506 high explosive was placed on top of the balloon. This explosive sheet weighed 3 grams per square inch. The standoff between the explosive and the steel wool sandwich was set at 4". A vacuum of about 25" was drawn on the bag. The explosive was detonated electrically from one corner of the sheet. The resultant structure was a shiny, highly compressed metal sheet quite flexible in nature with internal fibrous portions and having a degree of porosity. The sheet had a substantially uniform thickness of approximately .008".

Example 2.The same material referred to in Example 1 was used. The steel wool was positioned between steel shims in the polyethylene bag and taped together to form a sandwich having a tmckness of approximately A". In place of a balloon containing water, a standoff for the explosive was provided by seven sheets of thick blotting paper having a total thickness of .25". The same explosive referred to in Example 1 was then placed over the paper. A balloon filled with water was placed on top of the explosive sheet. A vacuum was drawn as in Example 1. The detonation of the explosive yielded a completely fused sheet of steel, .004" thick which was highly oxidized on its surface. It partially adhered to the steel shim.

Further experiments illustrated that more energy is required to fuse coarse fibers than fine fibers. This is probably due to the fact that fine fibers reach a fusing temperature faster when surrounded by high temperature gases than coarse fibers which have a much smaller exposed surface per unit weight. It has also been discovered that the lower the thermal-conductivity of the fibers the better the chances for fusion at the points of fibrous crossing.

Example 3.-The explosively formed structure formed in Example 1 was subject again to detonation under conditions indicated in Example 2. It tended to show less fusing than a non-precompressed sheet subject to the same total amount of explosive force. It is theorized that this is due to the lack of gases in the precompressed sheet at the time of the second treatment. Only a relatively little energy, generated by the shock wave is transformed into thermal energy to fuse the fibers, due to the lack of fiber deformation and frictional work.

The compacted and/or fused sheets are normally flexible and relatively strong. When they are only partially fused or fused with through pores formed in them they are particularly useful as filter material.

Example 4.The same material used in Example 1 was used and the procedure followed was the same. The resultant structure was sintered in a sintering oven under a reducing hydrogen atmosphere for one hour at 900 C. The sheet was then subject to the process of Example 1 once again, but the standoff distance was reduced to 1" of Water. This resultant product is a highly compacted sheet closely approaching the density of the solid metal.

The foregoing system may be used to fuse structures from filamentary crystals or whiskers. Such crystals may be formed of metallic and non-metallic elements, such as sapphire, iron, carbon, quartz, copper or silicon. Such crystals, as for example metal crystals, which have exceptional tensile strength will form relatively stronger structures than heretofore possible from the bulk metal which contains dislocations that Weaken it. In such process the explosive duration should be as short as possible and the material should be cooled as quickly as possible. Depending on the size of the material, the duration of the pressure wave may be preferably in the range of up to 1000 microseconds. It is theorized that if the explosion duration is of this maximum magnitude the metal whisker crystals will not recrystallize and thereby not change their properties.

The same system as described above may be used for forming pseudo-alloys having directional electrical and thermal conductivity properties. In this arrangement fibers or particles are distributed or imbedded into an oriented fiber web in selected directions. The resultant structure will yield a homogeneous dispersion of the distributed material in a solid mass. If fibers of high conductivity are oriented in one direction and fibers of a low conductivity in a different direction, a resultant product may be formed which has different gain factors in these two directions.

Also contemplated is the use of the foregoing process for forming laminated surfaces on a structure formed from webs of the type described. For example, an aluminum surface may be laminated onto a structure formed of the fibrous web by laying a sheet of aluminum adjacent the web during the high rate energy discharge process so that the aluminum is fused onto the surface of the structure to form a coating of aluminum.

Having now described my invention, I claim:

1. A method of forming a shaped structure comprising arranging a quantity of deformable fibers in a web adjacent to restraining means having a surface conforming to a desired shape, immersing said fibers and said surface in an energy transmitting medium, and thereafter rapidly discharging sutficient energy in said medium to cause said medium to transmit suflicient energy to move said fibers toward said restraining means at a velocity between approximately feet per second and a velocity such as to fragmentize said restraining means and to deform and bond said fibers into an integral mass having a surface configuration conforming with said restraining means surface.

2. A method of forming shaped structures comprising,

arranging a quantity of metal fibers in a Web adjacent to a restraining means having a surface conforming to a desired shape, immersing said fibers and said surface in an energy transmitting medium, and thereafter rapidly discharging sufficient energy in said medium to move said fibers toward said restraining means at a velocity between approximately 100 feet per second and a velocity such as to fragmentize said restraining means and to cause said medium to transmit sufiicient energy to deform and bond said fibers into an integral mass having a surface configuration conforming with said restraining means surface.

9 3. A method as set forth in claim 2 wherein said medium is nonoxidizing whereby oxidation of said metal fibers is minimized.

4. A method of forming shaped structures comprising,

arranging a quantity of metal fibers in a web of controlled thickness with one surface thereof adjacent to a restraining means having a surface conforming to a desired shape,

arranging energy means for rapidly discharging sufficient energy in said medium to move said fibers toward said restraining means at a velocity between approximately 100 feet per second and a velocity such as to fragmentize said restraining means and to compact said fibers into an integral mass against said restraining means with said energy means positioned on the side'of said Web opposite said one surface of said web,

and thereafter discharging said energy means for moving said fibers at said velocity to compact said fibers into an integral shape having a surface configuration conforming with said restraining means surface.

5. A method as set forth in claim 4 wherein sufiicient energy is discharged within said time period to partially melt said fibers into a homogeneous porous mass.

6. A method as set forth in claim 4 wherein said fibers are oriented in a preselected direction within said web.

7. A method as set forth in claim 4 wherein said web is immersed in a selected gas to provide an ambient atmosphere in which said fibers may be shaped.

8. A method as set forth in claim 7 wherein air is removed as an ambient atmosphere and another gas is substituted.

9. A method of forming shaped structures comprising,

arranging a quantity of metal fibers in a web of controlled thickness with one surface thereof adjacent to a restraining means having a surface conforming to a desired shape, evacuating air from adjacent said web and enveloping said Web in an energy transmitting medium,

arranging energy means for rapidly discharging sufficient energy in said medium to move said fibers toward said restraining means at a velocity between approximately 100 feet per second and a velocity such as to fragmentize said restraining means and to compact said fibers into an integral mass against said restraining means with said energy means positioned on the side of said web opposite said one surface of said web,

and thereafter discharging said energy means for moving said fibers at said velocity to transmit energy through said medium to compact said fibers into an integral shape having a surface configuration conforming with said restaraining means surface.

10. A method as set forth in claim 9 wherein said energy transmitting medium comprises a pressure transmitting fluid.

11. A method as set forth in claim 10 wherein said web is encased within a flexible substantially nonporous container.

12. A method as set forth in claim 11 wherein said container has contained Within it at least one rigid shim adjacent to said web.

13. A method as set forth in claim 10 wherein said restraining means comprises a die of solid material.

14. A method as set forth in claim 10 wherein sufficient energy is discharged within said time period to at least partially melt and thereby bond said fibers at their interstices.

15. A method of forming a shaped structure of controlled thickness between opposite surfaces comprising,

arranging a quantity of metal fibers in a web,

arranging said web with its thickness varied in preselected areas, positioning said web with one surface iii thereof adjacent to and conforming with a restraining means having a surface conforming with one of said desired structure surfaces, positioning a rigid shield over the other surface of said web, said shield having a surface conforming with the other of said structure surfaces, arranging on the other side of said shield energy means for rapidly discharging suflicient energy in said medium to move said fibers toward said restraining means at a velocity between approximately feet per second and a velocity such as to fragmentize said restraining means and to compact and at least partially fuse said fibers into an integral mass between said shield and said restraining means, and thereafter discharging said energy means for moving said fibers at said velocity to compact and at least partially fuse said Web into said shaped structure. 16. A method of forming a shaped alloy structure comprising,

forming a web of metal fibers with a dispersion therethrough of a second material divided in discrete particle size, arranging said web in a body of controlled thickness,

positioning said web with one surface thereof adjacent to and conforming with a restraining means having a surface conforming with a desired surface of said structure, arranging energy means for rapidly discharging sufficient energy in said medium to move said fibers toward said restraining means at a velocity between approximately 100 feet per second and a velocity such as to fragmentize said restraining means and to compact and fuse said fibers and particles into an alloyed mass against said restraining means with said energy means positioned on the side of said web opposite said one surface of said Web, and thereafter discharging said energy means for moving said fibers at said velocity to compact and fuse said fibers into an alloyed shape having a surface configuration conforming with said restraining means surface.

17. A method of forming structures having improved strength characteristics comprising,

forming a web of single crystal fibers with one surface thereof adjacent to a restraining means having a surface conforming to a desired shape,

arranging energy means for rapidly discharging sufficient energy over a time period not exceeding substantially 1,000 microseconds to compact and at least partially fuse said fibers into an integral mass against said restraining means with said energy means positioned on the side of said web opposite said one surface of said web,

thereafter discharging said energy means to cause said fibers to move toward said restraining means with a velocity sufficient to compact and at least partially fuse said fibers into an integral and at least partially fused shape having a surface configuration conforming with said restraining means surface.

18. A method as set forth in claim 17 whereinsaid fibers and selectively oriented.

References Cited in the file of this patent UNITED STATES PATENTS 2,648,125 McKenna et al Aug. 11, 1953 3,036,373 Drexelius May 29, 1962 3,036,374 Williams May 29, 1962 OTHER REFERENCES Pages 58-60, of Mechanical Engineering, vol. 82, No. 7, July 1960, published by ASME, 29 W. 39th St., New York 18, N.Y. 

1. A METHOD OF FORMING A SHAPED STRUCTURE COMPRISING ARRANGING A QUANTITY OF DEFORMABLE FIBERS IN A WEB ADJACENT TO RESTRAINING MEANS HAVING A SURFACE CONFORMING TO A DESIRED SHAPE, IMMERSING SAID FIBERS AND SAID SURFACE IN AN ENERGY TRANSMITTING MEDIUM, AND THEREAFTER RAPIDLY DISCHARGING SUFFICIENT ENERGY IN SAID MEDIUM TO CAUSE SAID MEDIUM TO TRANSMIT SUFFICIENT ENERGY TO MOVE SAID FIBERS TOWARD SAID RESTRAINING MEANS AT A VELOCITY BETWEEN APPROXIMATELY 100 FEET PER SECOND AND A VELOCITY SUCH AS TO FRAGMENTIZE SAID RESTRAINING MEANS AND TO DEFORM AND BOND SAID FIBERS 